Thread take-up mechanisms for sewing machines



Nov. 3, 1959 A. E. VAKTAR EFAL THREAD TAKE-UP MECHANISMS FOR sswms MACHINES 3 Sheets-Sheet 1 Filed Sept. 24, 1956 INVENTORS. Anfhony E. VO/(fOfmd BY Hans Ha k/ander 71M 9: r TORNEY WITNESS Nov. 3, 1959 A. E. VAKTAR ETA!- mmo TAKE-UP macmmrsms FOR SEWING mcnmzs Filed Sept. 24, 1956 3 Sheets-Sheet 2 INVENTORIS- Anthony E. Vakfar and BY Hans Hack/under WITNESS TORNE Y United States Patent THREAD TAKE-UP MECHANISMS FOR SEWING MACHINES Anthony E. Vaktar, Linden, and Hans Hncklander, Warren Township, N.J., asslgnors to The Singer Manufacturing Company, Elizabeth, NJ., in corporation of New Jersey Application September 24, 1956, Serial No. 611,600 7 Claims. (Cl. 112-241) The present invention relates to a thread take-up mechanism for sewing machines and particularly a looper thread take-up mechanism for a chain stitch sewing machine. The objects of the present invention are to provide an improved thread take-up mechanism that is eflicient in operation, dependable, durable, economical and can be readily adjusted to satisfy varying sewing conditions. Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently pre ferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

Fig. l is a vertical sectional view longitudinally of a sewing machine embodying the present invention.

Fig. 2 is a fragmentary plan view of the bed of the machine illustrated in Fig. 1, with the cloth plate removed, showing the looper thread takeup mechanism of the present invention.

Fig. 3 is a fragmentary sectional view taken substantially on the line 33 of Fig. 2 and illustrating the present looper thread take-up mechanism in elevation.

Fig. 4 is an enlarged fragmentary sectional view taken substantially on the line 44 of Fig. 2.

Figs. 5, 6 and 7 are sectional views similar to Fig. 4 but illustrating the mechanism in different positions of operation.

Fig. 8 is a detail sectional view taken substantially on the line 8-8 of Fig. 2.

The present invention is illustrated in the drawings as embodied in a sewing machine as disclosed in copending application Serial No. 609,836, filed September 14, 1956. Since the specific details of the machine do not form any part of the present invention, they are herein illustrated and described only insofar as believed to be necessary for an understanding of the present invention. For a more complete disclosure of the construction and operation of the machine, references may be had to application Serial No. 609,836.

With reference to the drawings, there is illustrated a sewing machine having a bed 1, a standard 2 rising from one end of the bed 1, and a bracket arm 3 carried by the standard 2 and terminating in a head 4 overhanging the bed 1. The bed 1 is divided by a transverse wall into a closed splash-lubricated compartment 6 and an open compartment 7.

The stitching mechanism comprises a needle bar 8 mounted in the head 4 for longitudinal reciprocation and carrying a pair of needles 9 at its lower end. The needle bar 8 is reciprocated by means of a collar 10 connectedbyalinklltoone endofarocklever 12 pivoted intermediate its ends on a pivot shaft 13 and connected at its otherendbyapitman 14toacrankona main shaft journaled in the compartment 6 of the bed. Cooperating with the needles 9 are a pair of endwise reciprocating threaded loopers 16 mounted upon a looper carrier 17 secured on a looper bar 18. The looper bar is mounted for endwise reciprocation in the wall 5 and a boss 19, and axial reciprocation as well as oscillation is imparted thereto by means of a connecting rod 20 connected through a universal joint 21 to the one end of the looper bar 18 within the compartment 6. At its other end the connecting rod 20 is connected through a universal joint 22 to a skewed crank pin 23 mounted on a crank plate 24 that is -in turn mounted upon a looper drive shaft 25 journaled transversely of the bed and connected by bevel gears 26 and 21 to the main shaft 15. It will be apparent that upon rotation of the looper drive shaft 25, the crank plate 24 will be rotated and the throw of the crank pin 23 will impart axial reciprocation to the looper bar 18 and the gyration thereof because of the skewed axis will impart oscillation to the looper bar 18. Anal reciprocation of the looper bar 18 ettects the advance and return or the loop seizing and loop shedding movements of the loopers 16, and the oscillation of the looper bar 18 effects the needle avoiding movements of the loopers 16.

1n the space 7 of the bed, there is provided a flat 28 on the wall 5, on which fiat 28 is secured a mounting plate 29 by means of screws 30. The mounting plate 29 has a channel or groove 31 which receives a base plate 32 of a sheet metal bracket 33, which base plate is adjustably secured to the mounting plate 29 by a screw 34 passing through an elongated slot 35 in the base plate 32 and threaded into the mounting plate 29. The base plate 32 has an integral upstanding arm 36 arranged longitudinally of the machine and carrying a lateraUy extending supporting arm 37 that is bent to provide an ear 38 arranged parallel to the arm 36. Aligned thread eyes or guides 39 and 40 are formed in the arm 36 and car 38 respectively, the eyes 39 and 40 defining a thread path transversely of the machine. The bracket 33 is arranged to receive the looper threads, designated T and T from the supply with the threads running through the thread eye 39 and then through the thread eye 40. A wire separator finger 41 is carried by the arm 36 and extends upwardly between the threads T and T; on the incoming side of the bracket 33. On the opposite side of the mounting plate 29 from the bracket 33 is a wire thread guide 42 adjustably secured by a screw 43 passing between two parallel portions of the wire to the plate 29. The guide 42 has two upstanding fingers 44 and 45. The looper thread T is directed around the finger 44 toward the inner one of the loopers 16 and the thread I, is directed around the finger 45 toward the outer one of the loopers 16.

Formed in the mounting plate 29 is a groove 46 arranged longitudinally of the machine. A stationary wire thread guiding or controlling element 47 is formed with an elliptical base portion 48 seated in the groove 46 and, in effect, defining an elongated slot through which passes a screw 49 that adjustably secures the element 47 to the plate 29. The element 47 has a vertically arranged arcuate portion 50 and a straight horizontal portion 51 which extends toward the lateral arm 37 of the bracket 33 and passes through a notch 52 in the arm 37 with the free end of the element 47 disposed beyond the arm 37. A second stationary wire thread guiding or controlling element 53 is formed with an elliptical base 54 seated in the groove 46 forwardly of the element 47 and is adjustably secured in the groove 46 by a screw 55. The element 53 includes a substantially straight generally vertical portion 56 disposed forwardly of the vertical portion 50 of the element 47 and a straight horizontal portion 57 arranged in spaced parallel relation vertically below the horizontal portion 51 of the element 47. The horizontal portion 57 of the element 53 passes through a notch 58 in the arm 37 with the free end thereof disposed beyond the arm 37.

The looper thread take-up mechanism acts upon the limbs of the looper threads T and T, between the thread eyes 39 and 40 and comprises an angle bracket 59, Fig. 3, including a vertical arm 60 that is adjustably secured to the looper carrier 17 by a screw 61 passing through an elongated slot 62 in the arm 60 and threaded into the looper carrier. The bracket 59 also includes a horizontal arm 63 to the outer end of which is secured by a screw 64 a take-up finger 65 formed from a continuous piece of wire that is bent back upon itself at substantially its midpoint, as at 66, to provide two spaced arms 67 and 68, having parallel free end portions 69 which underlie the head of the screw 64 on opposite sides thereof and which can be adjusted relative to the head of the screw 64 for adjustably securing the take-up finger 65 to the arm 63. The arms 67 and 68 of the take-up finger 65 are similar and include, in addition to the free end portion 69, a vertical portion 70 rising from the portion 69 and a forwardly and upwardly extending portion 71 that terminates in a generally vertical arcuate portion 72 presenting a convex edge to the threads T and T, and having the most advanced point thereof, designated 73, disposed adjacent to the horizontal portion 57 of the stationary element 53 so that upwardly from the point 73 the portion 72 is curved toward the loopcrs to define a throat 74 with the stationary element 47.

Since the take-up finger 65 is mounted upon the looper carrier 17, it will have the same motion as the loopcrs 16. To accommodate the needle avoiding motions of the loopcrs, the arcuate portions 72 of the arms 67 and 68 are spaced apart and spaced from the stationary ele ments 47 and 53 and from the arm 36 and car 38 of the bracket 33. The lead of the threads T and T, between the thread eyes 39 and 40 is through the space between the stationary thread guiding elements 47 and 53 and to the right of the take-up finger 65 as seen in Figs. 4-7. The successive actions of the take-up mechanism are illustrated in Figs. 4, 5, 6 and 7. In Fig. 4 the loopcrs 16 have completed the loop seizing or advancing motion and have begun the loop shedding or return motion. Upon the initial return motion of the loopcrs 16, the take-up finger 65 moves to the right and because of the slope of the arcuate portions 72 relative to the direction of travel, the threads T; and T, are moved into the throat 74. Upon the continued return motion of the loopcrs, the threads will be held in the throat 74 as it moves to the right in Fig. 4 and they will thus slide along the lower edge of the horizontal portion 51 of the element 47 to effect the take-up action.

In order to obtain proper stitch setting for a Federal type 401 double-locked two thread chain stitch, it is necessary that the tension on the looper thread be released after the needle has entered the loop in the looper thread and at the time that the needle thread loop from the previous stitch is released from the looper, Fig. 6, which is near the end the return motion of the looper. With a rotary cam looper thread take-up, such as shown in the U.S. patent of Clayton, No. 2,095,212, the cam can be designed to give the precise thread control desired. However, a rotary looper thread take-up has one very serious disadvantage which is that it will wind thread in the event that the thread should become broken and the end caught by the rotating components, and it will wind a huge quantity of thread in a very short time. Prior attempts to substitute a non-rotating looper thread take-up have not been successful since they did not provide the required thread control, and particularly, did not provide for cast-off of the looper threads at the time of stitch setting.

In accordance with the present invention, there is obtained by means of a non-rotating looper thread talte-up,

a unique take-up action. Upon the return motion of the looper, the take-up action is expanding a double limb of the looper thread along a straight line away from the thread eyes 39 and 40 to obtain a maximum take-up action. Toward the end of the return stroke, the return motion of the looper slows to a stop and then the looper starts the advance motion. At this time, there is only a little thread given up by the looper, requiring a reduced take-up action, and, as pointed out above, there must be a cast off or release of the looper thread at the time the needle thread loop slides off the looper. In the present construction, this take-up action and cast ofi is provided as seen in Figs. 5 and 6 respectively.

As seen in Fig. 5, when the points on the arcuate portions 72 of the take-up arms 67 and 68 which are at the same elevation as the horizontal portion 51 of the stationary element 47, pass beyond the end of the horizontal portion 51, the threads will be cammed downwardly by the cooperation of the arcuate portions 72 and 50, Fig. 5. To obtain this action, the arcuate portions 72 are sloped or inclined relative to the arcuate portion 50, which may be accomplished as shown by arranging the arcuate portions 72 slightly higher than the arcuate portion 50 so that as the points along the arcuate portions 72 successively pass the corresponding points of the arcuate portion 50 which are at the same horizontal elevation, the threads are moved progressively downward off the arcuate portion 50. During this time, there is the desired reduced take-up action efiected upon the threads T, and T since the arcuate portion 50 is formed on an are that approaches an are drawn from a center defined by the line between the thread eyes 39 and 40, and the limbs of thread are thus swung around the thread eyes 39 and 40 as well as expanded. At cast off, as seen in Fig. 6, the arcuate portions 72 of the take-up arms 67 and 68 have passed completely beyond the arcuate portion 50 of the element 47, and the threads T and T, slide onto the inclined portions 71. At this time, the radius from the eyes 39 and 40 to the take-up arms 67 and 68 decrease along the length of the arms and the threads are free to fall toward the element 53. Thereafter, as the loopcrs advance and require thread, the take up finger 65 advances and gives up thread. During the advance stroke of the looper the stationary thread guiding element 53 and the finger 65 cooperate to control the threads.

One of the advantages of the present construction is that the take-up finger 65 and the thread guiding elements 47 and 53 can be made from wire and can therefore be readily formed to adapt it for use with any specific sewing condition. At the same time, to vary the take-up characteristics, the take-up finger 65 is adjustable vertically by means of the screw 61 and horizontally by means of the screw 64, while the thread guiding elements 47 and 53 are adjustable in the groove 46.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Having thus set forth the nature of the invention, what we claim herein is:

1. In a sewing machine, a thread take-up mechanism comprising a take-up finger means for linear motion to said take-up finger, said finger having a curved thread engaging portion presenting a convex edge in the direction of take-up motion, a pair of thread guides defining a thread path transversely of the line of motion of said take-up finger, and a stationary element having a thread guiding edge comprising a first portion arranged generally in the direction of the line of motion of said take-up finger and cooperating with said take-up finger to expand a limb of thread extending between said thread guides in sliding engagement with said thread guiding edge upon the take-up motion of said finger to effect a take-up action on the thread, and a second portion form ing a smooth continuation of the straight portion and presenting a concave edge for cooperation with the linearly moving convex edge of said take-up finger to force the thread off the thread engaging portion of said take-up finger to effect cast off of the thread.

2. In a sewing machine, a thread take-up mechanism comprising a take-up finger, means for imparting linear motion to said take-up finger, a pair of thread guides defining a thread path transversely of the line of motion of said take-up finger, means defining a first thread guiding edge cooperating with said take-up finger to expand a limb of thread extending between said thread guides in sliding engagement with said thread guiding edge upon the take-up motion of said finger to effect a take-up action on the thread, and means defining a second thread guiding edge spaced from said first thread guiding edge for controlling the limb of thread upon the return motion of said take-up finger.

3. In a sewing machine, a thread take-up mechanism comprising a pair of thread guides defining a thread path, a take-up finger movable bodily in a plane between said thread guides and presenting a thread engaging portion sloped relative to the direction of motion of the take-up finger, and a stationary thread controlling element having a thread guiding edge including a first portion elongated generally in the direction of motion of said take-up finger and cooperating with the thread engaging portion of said take-up finger to define a throat for holding and expanding the thread limb extending between the thread guides, said thread engaging edge having a second portion sloped relative to the thread engaging portion of said take-up finger to force the thread off the thread engaging portion of said take-up finger to efiect cast off of the same.

4. In a sewing machine, a thread take-up mechanism comprising a pair of thread guides defining a thread path, a take-up finger movable bodily in a plane between said thread guides and having a curved thread engaging portion presenting a convex edge in the direction of take-up motion, and a stationary thread controlling element having a thread guiding edge including a first portion elongated in the direction of motion of said take-up finger and disposed between said thread guides on the same side of the line of motion of the leading point of said convex edge of said take-up finger as said thread guides to provide a throat for receiving a limb of thread extending between said thread guides and holding the same upon the take-up motion of said take-up finger to expand the limb of thread, and including a second portion forming a smooth continuation of the first portion and curved toward an are about the line defined by said thread guides to swing the limb of thread about said thread guides upon cooperation of said take-up finger with said second portion of said thread engaging edge and to etfect cast off of the limb of thread when said thread engaging portion of said take-up finger passes said second portion of said thread guiding edge, and a second stationary thread controlling element having a thread guiding edge for controlling the limb of thread after cast off and during the return motion of said take-up finger.

5. In a sewing machine having a bed, stitching mechanism including a looper carrier mounted in said bed and a threaded chain stitch looper mounted on said looper carrier and adapted to cooperate with a needle in the formation of chain stitches, means for actuating said looper carried to impart advance and return motions to said looper, and looper thread take-up mechanism comprising a take-up finger mounted on said looper carrier, 11 pair of stationary thread guides defining a thread path transversely of and in the path of motion of said take-up finger, and a stationary element mounted in said bed and having a thread guiding edge cooperating with said take-up finger upon the return motion of said looper to effect a take-up action on a limb of looper. thread extending between said thread guides.

6. In a sewing machine, a thread take-up mechanism comprising a pair of thread guides defining a thread path, a take-up finger movable between said thread guides and having a curved thread engaging portion presenting a convex edge in the direction of motion and arranged transversely of the thread path for engaging a limb of thread extending between said thread guides and expanding the same, and a stationary element having a thread guiding edge cooperating with said finger during the take-up motion to position the thread on the thread engaging portion thereof, said thread guiding edge having a first portion extending generally in the direction of motion of said finger and cooperating with the thread engaging portion of said take-up finger to define a throat, and a second portion forming a smooth continuation of the first portion and being sloped relatively to the thread engaging portion of said finger to swing the expanded limb of thread about said thread guides.

7. In a sewing machine, a thread take-up mechanism comprising a movable take-up finger including an elongated smooth thread engaging portion arranged generally normal to the direction of motion thereof and along which the thread will slide during the take-up action, a pair of thread guides defining a thread path transversely of the path of motion of the thread engaging portion of said take-up finger, and a stationary element having a thread guiding edge, said thread guiding edge including a first portion extending generally in the direction of the path of motion of said take-up finger and cooperating with said take-up finger to effect a take-up action on a limb of thread extending between said guides, and a second portion forming a smooth continuation of said first portion and extending generally normal to said first portion to force the thread off the thread engaging portion of said take-up finger to effect cast ofi of the thread.

References Cited in the file of this patent UNITED STATES PATENTS 1,328,023 Weis Ian. 13, 1920 1,884,028 Lutz Oct. 25, 1932 2,730,060 Schoij et al, Jan. 10, 1955 

